by Jay Reynolds Freeman
The heavy tropical rainfall was dismaying, but our determined little convoy climbed the Saddle Road, windshield wipers flicking boldly. We eventually reached cloud base, and though enough daytime heat remained in the lava to keep visibility up at the surface, large drops falling from close, gray sky suggested a poor evening for astronomy. Yet as the terrain leveled off, we scooted out from under the clouds, and what do you know? The sky was and clear, and the sun was shining. Bits of cloud spilling onto the saddle from the east tickled the two mammoth volcanos, but most of the heavens were a deep, pellucid blue.
Weather on the east side of the big island resembles the marine layer of the central California coast, with two differences. First, the prevailing trade winds in Hawaii are out of the east. Second, the vertical scale is about five times as great. The top of the layer is nearly 2 Km above sea level, which makes the clouds thick enough to deliver considerable precipitation. Hilo averages over three meters of rain a year, most of it from late afternoon till dawn. At that time, the heat of the day has diminished, and no longer counteracts condensation as the wet air mass flows upslope between the volcanos.
A strong temperature inversion defines the top of the layer. Clouds above are extremely rare. They occur for the most part only when there is a weather system in the area. But trade-wind showers are the daily fare of eastern Hawaii -- there was always at least some rain on the drive up the Saddle Road in late afternoon or early evening, and lots more coming down in the small hours of the morn. Yet for the rest of my visit, the night sky at the Visitor Center remained clear, dark, and dry. The lower clouds even helped: Hilo generally uses full cutoff outdoor lighting, but a mile of wet stuff reduced the light still further. I saw no light domes from Mauna Kea.
My friends' elderly Toyota subcompact slowed to nearly a crawl on the seventeen-percent grades of the last few miles before the Visitor Center, but we finally made it. The first task was a photo session. I had bought a tacky plastic lei, made in China, with colors carefully selected to match nothing else in my possession. We got several photos of me standing beside my 10-inch Dobson, wearing lei, sunglasses, many disorganized layers of warm clothes, down-filled gloves, and my decrepit furry Russian infantryman's hat with its ear flaps turned haphazardly down. The definitive images have trash and recycling barrels in the background -- they were out of the wind, so I used them as chart tables.
My lists of objects started far west of Crux, in Carina and Vela, including many targets setting in twilight. Thus the night's observing followed a pattern familiar to Messier marathon fans and other deep-sky die-hards: Manic observing early, as I chased stuff in the southwest before it went away, followed by a more relaxing time of it later on. My lists were intentionally optimistic as to how far west I could work, since I wasn't sure when twilight ended, or how low the southwest horizon was. Even for areas I could get to, there was more stuff than I could see in an evening, so the mania persisted for several nights.
My planning and list-making paid off, though. Even in sky I had never seen before, star-hopping was easy. I would scan naked-eye to identify some bright star that was on the Millennium Star Atlas chart of the moment, get it in the finder and then in the main telescope, and star hop from there. I worked one facing pair of Millennium charts from west to east, then turned a page over and continued eastward. It was rare that I had to use the finder, though some times it was faster and easier to do so, than to star-hop a long distance with an actual field of view, in my 12 mm Brandon at 106x, of less than half a degree. That Brandon was the only eyepiece I used with the 10-inch during the entire trip. If I omit to mention magnification again, assume 106x.
Most objects I was seeking in that part of the sky were open clusters, with a few planetaries or other nebulae for variety. Central Vela is as far from the bearing of the center of our galaxy as is central Cygnus, only in the opposite direction, so it would not be surprising to find the Milky Way from Vela through Carina, Crux, and Centaurus approximately as rich as the sweep from Deneb down through the Aquila, which is more familiar to northern observers.
In fact, as far as galactic clusters go, southern observers have rather the advantage, for this part of the Milky way seems to contain more bright clusters -- things that look like M6 and M7 -- than does the opposite, northern sector. I am reluctant to write a shopping-list observing report -- you can get dimensions, magnitudes, and star counts from any number of atlases and catalogs, and my exclamations of awe and wonder will not have the nearly the impact of your own, when you see these objects first-hand. Nevertheless, let me mention a few highlights, though by no means all of them.
NGC 3532 is a large open cluster a few degrees east and a little north of the eta Carina complex. At a glance in the 10-inch's 6x30 finder, or with the naked eye, it was possible to confuse the two for a moment. NGC 2000.0 gives it a magnitude of 3 and a diameter of nearly a degree. Its scattering of stars seems homogeneously distributed across its width, and does not contain any that seem anomalously bright. NGC 7789 might look like this if it were three or four times closer, with each of its individual stars ten or twenty times greater in apparent brightness. The stars were bright enough that the cluster was well resolved in my 14x70 binocular, as well as in the telescope.
About five degrees south of eta Carina lies IC 2602, the Southern Pleiades, an even brighter cluster -- magnitude 1.9 -- with a very different character. It doesn't look like its namesake in detail, but bears a resemblance in number and distribution of members. Grouped around theta Carinae are a coarse handful of fairly bright stars, with additional fainter ones as background, but not in such quantity as to dominate the cluster. The northern Pleiades might well look this way if they were a little farther off, and were viewed from an unfamiliar angle. At 64d 20' south declination, IC 2602 was one of the most southerly deep-sky objects I observed, so far south that I could not easily see it from any of the locations where I set up my telescope. My observation was with my 14x70, for which it is a fine object.
NGC 3114, in Carina, is a bit more than five degrees west of eta. It is interim in character between the last two clusters mentioned, though not as large or as bright. The 10-inch resolved it, and I suspect the binocular would have as well, though I did not get around to using the 14x70 on this object
NGC 3766 is a cluster in Centaurus, about a degree and a half north of lambda. It contains a quite dense knot of stars about ten arc minutes across. The 10-inch resolved it.
NGC 5662, in eastern Centaurus, is not as southerly. It is five degrees north of Beta Centauri, and a bit west. At magnitude 5.5, it is no doubt a naked-eye object, and my failure to notice it, as well as many others, follows from the fact that I am nearsighted, and spend most of my time at star parties with my glasses safely squirreled in the car, while I experience the restricted limiting magnitude that comes from having all the stars greatly out of focus. This fairly loose small cluster was pretty in the 10-inch, and was granular to resolved in the big binocular later in the week.
After a few hours' observing, I found that there was nothing I wanted to look at that was about to set on me, so I lowered my telescope from its carrying-case stand and took a break from sweeping the southern horizons. I decided to look at some Messier objects, not only because a Messier survey is something I do with most telescopes and binoculars I possess, but also as a way of evaluating both site and southern objects against a familiar yardstick.
These views confirmed what I already knew about Mauna Kea -- it is a wonderful place. The Trifid Nebula shown resplendent in clear nursery colors, pale pastel pink in the ionized-gas "trifid" part, and soft baby blue in the reflection nebula, looking much like the images in many astronomical coffee-table picture books. M17 showed feathery detail on the body of the swan, and revealed portions of the vast loop of gas that lies beneath. On a later night, M27 appeared as a fat, stubby, blunt-pointed spindle, that might have been a cartoonist's caricature of a cigar -- but the bright cigar band was the familiar apple-core shape, that is all most observers see at lesser sites.
As the heavens rotated, I continued my southern-sky survey eastward, into Norma, Ara, and a corner of Pavo, picking off objects as they cleared the south horizon. Perhaps the best showpiece object for the remainder of the evening was the beautiful globular cluster NGC 6752, a hair shy of 60 degrees south, in northern Pavo. This cluster is larger and a half magnitude brighter than M13, though it is nowhere near as fine an object as omega Centauri. NGC 6752 appeared granular to resolved in the 10-inch, at 106x.
By 2:30 AM I was beginning to be very tired. My biological clock was only just unsetting from a place where dawn was breaking -- so I packed the telescope and drove back to Hilo. I had looked at 148 objects that night, 123 of which I had never seen before. Not bad, and four nights still to go.